On 2021-06-23 08:57, Johannes Berg wrote:
On Mon, 2021-04-26 at 12:05 -0700, Aloka Dixit wrote:
Hm wait, didn't I see the same code in cfg80211 - maybe cfg80211 should
just pass the pointer?
static int ieee80211_del_iface(struct wiphy *wiphy, struct
wireless_dev *wdev)
{
+ struct ieee80211_sub_if_data *sdata =
IEEE80211_WDEV_TO_SUB_IF(wdev);
+ struct ieee80211_local *local;
+ struct ieee80211_vif *vif;
+
+ if (!sdata)
+ return 0;
+
+ local = sdata->local;
+ vif = &sdata->vif;
+ if (vif->type == NL80211_IFTYPE_AP &&
+ ieee80211_hw_check(&local->hw, SUPPORTS_MBSSID_AP)) {
+ if (vif->mbssid.flags & IEEE80211_VIF_MBSSID_TX) {
+ struct ieee80211_sub_if_data *child, *tmpsdata;
+
+ wiphy_unlock(local->hw.wiphy);
+ mutex_lock(&local->iflist_mtx);
I really don't think you can drop the locking like that in the middle
of
something. That's almost always a recipe for disaster.
@@ -375,6 +375,18 @@ static void ieee80211_do_stop(struct
ieee80211_sub_if_data *sdata, bool going_do
struct cfg80211_chan_def chandef;
bool cancel_scan;
struct cfg80211_nan_func *func;
+ struct ieee80211_sub_if_data *parent;
+
+ if (sdata->vif.type == NL80211_IFTYPE_AP &&
+ ieee80211_hw_check(&local->hw, SUPPORTS_MBSSID_AP) &&
+ sdata->vif.mbssid.flags & IEEE80211_VIF_MBSSID_NON_TX) {
+ parent = vif_to_sdata(sdata->vif.mbssid.parent);
+ if (parent && ieee80211_sdata_running(parent)) {
+ wiphy_unlock(local->hw.wiphy);
+ dev_close(parent->wdev.netdev);
+ wiphy_lock(local->hw.wiphy);
Same here.
johannes
Hi Johannes,
Thanks for the comments, will go through all, but need your help with
this particular one -
I'm not able to come up with a different solution which does not cause a
deadlock by continuing to hold wiphy_lock() as we discussed last time
that dev_close() will in turn call into cfg80211.
You had suggested looking at dev_close() for VLAN, that code also
doesn't lock wiphy_lock hence I did same here but locked
'local->iflist_mtx'. Dropping both won't be good for sure.
Can you please suggest a better way? I'm really not able to come up with
one.
Thanks.
